A contingency table (
tableau de contingenc/à double entrées) is a table of the unique values of a vector by the number of times this value is present.
# picking 50 values within [0,10] vect <- sample(0:10, 50, replace = TRUE) table(vect) # 0 1 2 3 4 5 6 7 8 9 10 # 4 6 4 6 5 5 5 6 6 1 2
You can read that each of your eleven values was at least picked once. For instance, we picked $10$ twice.
You can use
prop.table to get the frequency of each value instead of the number of occurrences.
prop.table(table(v), 1)(line only)
prop.table(table(v), 2)(column only)
More complex tables
If you are calling a table like the code above, so while providing a qualitative variable (the unique values), and a quantitative variable (the values)
Then you may try to use
xtabs(~ qual + quant, ech)
The main difference is that
xtabs is using formulas, so when you learned them, you will be able to do quite the great contingency tables.